A rapid,specific and simple method was established for the quantitative determination of active components in N-catalyst by proton nuclear magnetic resonance spectroscopy.1H NMR spectra were obtained using CD3OD as solvent and hydroquinone as the internal standard with suitable acquisition time and delay time.By quantifying with the optimized experiment parameters,the average results of the active components,TBP,PA-DCP-TiCl3,DCP-TiCl3 and DNBP were 0.21%,0.58%,1.21%and 5.82%with their RSDs of 0.75%，0.89%，0.41%and 0.35%,respectively,which were in accordance with those measured by HPLC.This method was validated for the quantitative determination of active components in N-catalyst with no need of the standard reference compound.In the study of the chemical structures of the active components in N-catalyst by NMR,their contents could also be determined simultaneously.It provided a new way for the quantitative determination of the electron donor in preparation of N-catalyst.